1Section on Experimental Radiology, IDM of the Helmholtz Center Munich at the University Tübingen, German Center for Diabetes Research (DZD), Tuebingen, Germany, 2Department of Diagnostic and Interventional Radiology, Section on Experimental Radiology, Tuebingen, Germany, 3Department of Endocrinology and Diabetology, Angiology, Nephrology and Clinical Chemistry, IDM of the Helmholtz Center Munich at the University Tübingen, German Center for Diabetes Research (DZD), Tuebingen, Germany, 4Department of Diagnostic and Interventional Radiology, University Hospital Tübingen, Tuebingen, Germany, 5Section on Experimental Radiology, University Hospital Tübingen, Tuebingen, Germany